The present invention relates to a method for making an electrical circuit board and more particularly, to a method for making a multi-layer electrical circuit board having pipes, tunnels and/or caverns which are formed within the circuit board and/or through various portions of the circuit board, and which allow heat emanating from components which are contained within the circuit board to be efficiently dissipated.
Multi-layer circuit boards contain and/or include electrical components which selectively and operatively populate opposed first and second surfaces (i.e., top and bottom surfaces) of each board (or other respective interior portions of each board), thereby desirably allowing each of the electrical circuit boards to contain and/or include a relatively large amount of electrical components which efficiently and densely populate the respective boards.
Due to the relatively dense component population, substantial amounts of heat are produced and/or generated within relatively small areas of the circuit boards, This generated heat undesirably prevents the components front properly functioning and may even irrevocably damage or destroy these components. Therefore it is desirable to form, create and/or manufacture circuit boards that are adapted to disperse and/or dissipate heat away from such heat producing components.
Pipes, tunnels and/or caverns, commonly referred to as xe2x80x9cheat pipesxe2x80x9d, may be used to disperse, dissipate and/or translate heat within these multi-layer circuit boards. Conventional heat pipes typically comprise an elongated material which forms a pair of open ends and which further forms a tunnel extending down the length of the elongated material and communicating with each of the open ends. By way of example and without limitation, a conventional heat pipe in typically operatively placed within an electronic assembly such that a first portion of the pipe is disposed near a warm or heat emitting component of the equipment and a second portion of the pipe is disposed near a cooler or heat absorbing area of the assembly, thereby allowing the pipe to transfer heat away from the heat emitting component toward the cooler or heat absorbing area.
One drawback associated with these conventional heat pipes is that they are typically made and/or manufactured from xe2x80x9cadditionalxe2x80x9d materials that are not needed for the functioning of the electronics equipment within which the heat pipes reside. Employing heat pipes which use additional materials is especially undesirable in a multi-layer circuit board which is designed to support and/or contain several electrical components in a relatively small amount of space. Particularly, such additional materials add both unwanted size and weight to multi-layer circuit boards.
Consequently, there is a need for circuit boards created by a method which allows many small electrical components to densely populate respective layers within the circuit boards, while still allowing heat to be dissipated and/or dispersed away from heat-emitting components. Specifically, there is a need for a method of creating heat pipes within multi-layer circuit boards which are integrally formed within the circuit boards such that very little xe2x80x9cexcessxe2x80x9d or additional material is needed to create the beat pipes.
It is a first object of the present invention to provide a method for forming heat pipes within multi-layer circuit boards which overcomes the various previously delineated drawbacks of conventional heat pipes.
It is a second object of the present invention to provide heat pipes that are integrally manufactured from the original materials that are used when making a multi-layer circuit board.
According to a first aspect of the present invention a circuit board is disclosed. The circuit board includes a first and second pre-circuit assembly each including a first and second core metal portion, the first and second core metal portions respectively including a first and second channel; wherein the first pre-circuit assembly is attached to the second pre-circuit assembly such that the first and second channels cooperatively form a heat pipe.
According to a second aspect of the present invention, a method for producing a multi-layer circuit board having a heat pipe is disclosed. The method includes the steps of: providing a first and second pre-circuit assembly respectively having a first and second core metal portion; applying protective layers to the pre-circuit assemblies, effective to leave a first exposed portion on the first core metal portion and a second exposed portion on the second core metal portion; removing the first and second exposed portions to respectively form a first and second channel within the first and second core metal portions; and attaching the first pre-circuit assembly to the second pre-circuit assembly effective to cause the first and second channel to cooperatively form a pipe within the circuit board.